A prism is a device that may be used to disperse white light into the visible spectrum of colors. The visible spectrum of colors is commonly referred to as a “rainbow” due to the prismatic effect of rain droplets on rays of sunlight that pass through such droplets. Equilateral prisms are typically used for the dispersion of light into its component colors. Light incident at an oblique angle to the first face is dispersed according to its wavelength and emerges as a visible spectrum from the opposite face of the prism.
In addition to the potential for use in creating a pleasing display of colors, prisms are also very useful as components in certain optical systems. For example, prisms may be used to redirect or deviate an optical beam or rays or to erect an inverted image. Prisms that are commonly used in optical systems or as optical devices include right angle prisms, dove prisms, penta prisms, retro-reflectors, and precision wedge prisms.
Prisms are typically made from solid pieces of optical material such as glass or quartz. The faces of the prism are normally flat with the non-optical surfaces being left in the ground condition. The optically active faces are further ground and polished to a pre-specified degree of flatness. Prisms are usually more difficult to fabricate than mirrors or windows because several surfaces must be held in precise geometrical relationships to one another. Some prisms, such as retro-reflectors, rely greatly on the precision of these geometrical relationships. Thus, carefully controlling prism angles makes it possible to perform interesting and useful manipulations on the imaging light entering the prism.
Because light dispersing prisms are precision crafted instruments, in many cases they tend to be fragile, expensive, and not widely or immediately available for use in or as consumer products. Additionally, large spectrum forming prisms can be unwieldy, and the emergent spectral beam is only somewhat directable and must be accomplished by rotating the entire prism. Furthermore, rigid design compromises are often required to effectively control light dispersion while reducing reflection losses.
Thus, because prisms can be used as devices for teaching scientific principles to children or adults, for creating pleasing decorative spectral displays, and for a variety of technical purposes, there is a need for a less expensive prismatic device that performs the same or similar functions as the currently available glass or quartz prisms.